Fort Worth residents got their first sight of flying machines in 1911 when the International Aviators National Tour was lured to town by Amon G. Carter, Sr. That same year the first “air mail” letter was delivered. During World War I, the U.S., Canada, and Britain jointly established three airfields where 2,000 pilots trained. The city’s first airport, Meacham Field, opened in 1925. Texas Air Transport began regular mail and passenger service in 1928; it became American Airlines in 1934. Thousands of B-24 “Liberator” bombers were built in Fort Worth during World War II. Pilots trained at adjacent Tarrant Air Field, renamed Carswell Air Force Base in 1948. The site became the Naval Air Station Joint Reserve Base in 1994. Known as an aviation manufacturing center for bombers, fighter planes, helicopters, and commercial aircraft, Fort Worth also became a major transportation center in 1974 with the opening of DFW International Airport.